For a qualitative or quantitative determination of various components contained in a sample, a chromatograph mass spectrometer is widely used, which includes a chromatograph, such as a gas chromatograph (GC) or liquid chromatograph (LC), combined with a mass analyzer, such as a quadrupole mass analyzer (for example, see Patent Literature 1).
In the case where a chromatograph mass spectrometer is used for checking a plurality of residual agricultural chemicals or other impurities contained in a sample (such as food), one or more ions (“target ions”) are set for each of the residual agricultural chemicals to be checked (“target components”), and a selected ion monitoring (SIM) measurement for sequentially and repeatedly detecting those ions is performed to obtain a mass chromatogram for each target component. In the case of a triple quadrupole mass spectrometer or similar type of mass analyzer including front and rear mass filters with a collision cell sandwiched in between, one or more combinations of the precursor ion and product ion are set for each of the target components, and a multiple reaction monitoring (MRM) measurement for sequentially and repeatedly detecting those combinations of the ions is performed to obtain a mass chromatogram for each target component.
In the aforementioned measurement, predetermined voltages which are suited for the detection of the first target ion are initially applied to the relevant sections of the mass spectrometer (the ionizer, ion optical system, mass filter, detector, etc.), and the first target ion is detected for a specific period of time. Subsequently, the voltages applied to those sections are changed to the voltages which are suited for the detection of the second target ion, and the second target ion is detected for a specific period of time. In this manner, all target ions are sequentially subjected to the measurement, and such a cycle of measurements is repeatedly performed to acquire a series of detection signals for each target ion. From the detection signals acquired for each target ion, a mass chromatogram corresponding to the target component is obtained.